A bird beak is the most important resource it has, and every species has one solely designed for survival. Birds use beaks for just about everything: building nests, feeding their young ...

Yet, a beak can make all the difference in a bird's silhouette. It can also tell you what kind of diet this bird lives off.

Under these drastically changing conditions, the struggle to survive favored the larger birds with deep, strong beaks for opening the hard seeds. Smaller finches with less-powerful beaks perished.